1. Field of the Invention
The present invention relates to a method for reducing power consumption of a base station in a wireless communication system.
2. Description of the Related Art
Recently, a wireless communication system has been developed with a hierarchical cell structure in which two or more base stations are hierarchically operated. An example of such a wireless communication system is illustrated in FIG. 1.
FIG. 1 illustrates a wireless communication system with a hierarchical cell structure according to the related art.
Referring to FIG. 1, the wireless communication system includes an upper base station 100 and a lower base station 120. The upper base station 100 provides a macro cell coverage 110, including a cell coverage 130 of the lower base station 120. Further, the lower base station 120 has the cell coverage 130 corresponding to a part of the cell coverage 110 of the upper base station 100.
In the above described structure of the wireless communication system, when the traffic load in a specific area 130 within the cell coverage 110 of the upper base station 100 rapidly increases, there is an advantage in that the increased traffic can be efficiently handled without extension or relocation of base station installations based on the lower base station provided in the corresponding area 130.
In a wireless communication system, traffic load varies over time at a certain period (e.g., 24 hours, one week, and the like). That is, in a time zone in which frequent use of the wireless communication system occurs, such as a business time zone, a relatively large amount of traffic occurs with an increase of users. Contrarily, in a midnight time zone, a relatively small amount of traffic occurs.
In the wireless communication system, in order to smoothly provide service to users even in a time zone in which a traffic load is the highest, the capacity of a base station is generally set to a capacity capable of facilitating traffic handling in the time zone in which the traffic load is the highest.
Further, in a wireless communication system according to the related art, a base station performs basic operations for normally providing service even in a time zone in which the traffic load is relatively low. As an example, these basic operations include operations for system information transmission, primary/secondary synchronizing signal transmission, reference signal transmission, and the like.
As the basic operations are performed, a considerable amount of power is consumed in the base station. More specifically, assuming that the base station consumes 100% of reference power to handle maximum traffic, about 52% of the reference power may be continuously consumed to perform the basic operations in the base station.
Even when there is no traffic within the cell coverage of the base station, the base station performs the basic operations and thus continuously consumes power. More particularly, in a wireless communication system with a hierarchical cell structure, there is a problem in that a plurality of lower base stations are used and therefore power consumption of base stations within a corresponding cell further increases.